JP7622779B2 - Resist underlayer film forming composition containing polymer having alicyclic compound terminal - Google Patents

Description

The present invention relates to a composition used in lithography processes in semiconductor manufacturing, particularly in cutting-edge lithography processes (ArF, EUV, EB, etc.). It also relates to a method for manufacturing a substrate with a resist pattern to which the resist underlayer film is applied, and a method for manufacturing a semiconductor device.

Conventionally, in the manufacture of semiconductor devices, microfabrication by lithography using a resist composition has been performed. The microfabrication is a processing method in which a thin film of a photoresist composition is formed on a semiconductor substrate such as a silicon wafer, and the thin film is irradiated with active light such as ultraviolet light through a mask pattern on which a device pattern is drawn, developed, and the substrate is etched using the obtained photoresist pattern as a protective film to form fine irregularities on the substrate surface corresponding to the pattern. In recent years, the integration density of semiconductor devices has increased, and in addition to the conventionally used i-line (wavelength 365 nm), KrF excimer laser (wavelength 248 nm), and ArF excimer laser (wavelength 193 nm), the practical use of EUV light (wavelength 13.5 nm) or EB (electron beam) is being considered for cutting-edge microfabrication. As a result, the diffuse reflection of active light from the semiconductor substrate and the influence of standing waves have become major problems. In order to solve this problem, a method of providing an anti-reflective coating (Bottom Anti-Reflective Coating: BARC) between the resist and the semiconductor substrate has been widely studied. The anti-reflective coating is also called a resist underlayer film. As such an anti-reflective coating, many studies have been conducted on organic anti-reflective coatings made of polymers having light-absorbing sites, etc., because of their ease of use.
Patent Document 1 discloses a resist underlayer film-forming composition for use in a lithography process for manufacturing a semiconductor device, the composition containing a polymer having a repeating unit structure having a polycyclic aliphatic ring in the main chain of the polymer. Patent Document 2 discloses a resist underlayer film-forming composition for lithography, the resist underlayer film-forming composition containing a polymer having a specific structure at its terminal.

JP 2009-093162 A International Publication No. 2013/141015

The properties required for the resist underlayer film include, for example, that it does not intermix with the resist film formed on the upper layer (that is, that it is insoluble in a resist solvent) and that it has a faster dry etching rate than the resist film.
In the case of lithography involving EUV exposure, the line width of the formed resist pattern is 32 nm or less, and the resist underlayer film for EUV exposure is formed to a thinner film thickness than before. When forming such a thin film, pinholes and aggregation are likely to occur due to the influence of the substrate surface, the polymer used, etc., making it difficult to form a uniform film without defects.
On the other hand, when forming a resist pattern, a method may be adopted in which a solvent capable of dissolving the resist film, usually an organic solvent, is used to remove the unexposed portion of the resist film in the development step, leaving the exposed portion of the resist film as a resist pattern. In such a negative development process, improving the adhesion of the resist pattern is a major issue.
There is also a demand for suppressing deterioration of LWR (Line Width Roughness) during resist pattern formation, forming a resist pattern having a good rectangular shape, and improving resist sensitivity.

The present invention aims to provide a composition for forming a resist underlayer film capable of forming a desired resist pattern, which solves the above problems, and a method for forming a resist pattern using the resist underlayer film-forming composition.

The present invention encompasses the following:
[1] A composition for forming a resist underlayer film, comprising, at a terminal of a polymer, an aliphatic ring in which a carbon-carbon bond may be interrupted by a heteroatom and which may be substituted by a substituent, and further comprising an organic solvent.
[2] The resist underlayer film forming composition according to [1], wherein the aliphatic ring is a monocyclic or polycyclic aliphatic ring having 3 to 10 carbon atoms.
[3] The resist underlayer film forming composition according to [2], wherein the polycyclic aliphatic ring is a bicyclo ring or a tricyclo ring.
[4] The resist underlayer film forming composition according to any one of [1] to [3], wherein the aliphatic ring has at least one unsaturated bond.
[5] The resist underlayer film forming composition according to any one of items [1] to [4], wherein the substituent is selected from a hydroxy group, a linear or branched alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an acyloxy group having 1 to 10 carbon atoms, and a carboxy group.

[6] The resist underlayer film forming composition according to any one of [1] to [5], wherein the polymer has at least one structural unit represented by the following formula (3) in the main chain.

(In formula (3), A ₁ , A ₂ , A ₃ , A ₄ , A ₅ and A ₆ each independently represent a hydrogen atom, a methyl group or an ethyl group, Q ₁ represents a divalent organic group, and m ₁ and m ₂ each independently represent 0 or 1.)
[7] The resist underlayer film forming composition according to [6], wherein in the formula (3), Q ₁ represents a divalent organic group represented by the following formula (5):

(In the formula, Y represents a divalent group represented by the following formula (6) or formula (7).)

(In the formula, R ₆ and R ₇ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 3 to 6 carbon atoms, a benzyl group, or a phenyl group, and the phenyl group may be substituted with at least one selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, and an alkylthio group having 1 to 6 carbon atoms, or R ₆ and R ₇ may be bonded to each other to form a ring having 3 to 6 carbon atoms together with the carbon atoms bonded to R ₆ and R _7. )
[8] The resist underlayer film forming composition according to any one of [1] to [7], wherein the polymer further contains a disulfide bond in a main chain.
[9] The resist underlayer film forming composition according to any one of [1] to [8], further comprising a curing catalyst.
[10] The resist underlayer film forming composition according to any one of items [1] to [9], further comprising a crosslinking agent.
[11] A resist underlayer film, which is a fired product of a coating film comprising the resist underlayer film forming composition according to any one of [1] to [10].
[12] A method for producing a patterned substrate, comprising the steps of: applying the resist underlayer film forming composition according to any one of [1] to [10] onto a semiconductor substrate and baking the composition to form a resist underlayer film; applying a resist onto the resist underlayer film and baking the composition to form a resist film; exposing the resist underlayer film and the semiconductor substrate covered with the resist; and developing and patterning the resist film after exposure.
[13] A step of forming a resist underlayer film on a semiconductor substrate, the resist underlayer film being composed of the resist underlayer film forming composition according to any one of [1] to [10];
forming a resist film on the resist underlayer film;
forming a resist pattern by irradiating the resist film with light or an electron beam and then developing it;
forming a patterned resist underlayer film by etching the resist underlayer film through the formed resist pattern;
processing a semiconductor substrate using the patterned resist underlayer film;
A method for manufacturing a semiconductor device, comprising:

The resist underlayer film forming composition for lithography of the present invention is characterized in that the end of the polymer (or polymeric material) contained in the resist underlayer film forming composition is capped with an aliphatic ring in which the carbon-carbon bond may be interrupted by a heteroatom and an aliphatic ring which may be further substituted with a substituent, and is a composition containing such a polymer and an organic solvent, and preferably further a crosslinking agent and/or a compound (curing catalyst) that promotes the crosslinking reaction. By being configured in this way, the resist underlayer film forming composition for lithography of the present application can achieve the formation of a resist pattern having a good rectangular shape (no pattern collapse), suppression of deterioration of LWR during resist pattern formation, and improvement of sensitivity.

<Terminology explanation>
The terms used in the present invention have the following definitions unless otherwise specified.

Examples of "alkyl groups having 1 to 10 carbon atoms" include methyl, ethyl, n-propyl, i-propyl, cyclopropyl, n-butyl, i-butyl, s-butyl, t-butyl, cyclobutyl, 1-methyl-cyclopropyl, 2-methyl-cyclopropyl, n-pentyl, 1-methyl-n-butyl, 2-methyl-n-butyl, 3-methyl-n-butyl, 1,1-dimethyl-n-propyl, 1,2-dimethyl-n-propyl, 2,2-dimethyl-n-propyl, 1-ethyl-n-propyl, cyclopentyl, 1-methyl-cyclobutyl, 2-methyl-cyclobutyl, 3-methyl-cyclopropyl, n-hexyl group, 1-methyl-n-pentyl group, 2-methyl-n-pentyl group, 3-methyl-n-pentyl group, 4-methyl-n-pentyl group, 1,1-dimethyl-n-butyl group, 1,2-dimethyl-n-butyl group, 1,3-dimethyl-n-butyl group, 2,2-dimethyl-n-butyl group, 2,3-dimethyl-n-butyl group, 3,3-dimethyl-n-butyl group, 1-ethyl-n-butyl group, 2-ethyl-n-butyl group, 1,1,2-trimethyl-n-propyl group, 1,2 , 2-trimethyl-n-propyl group, 1-ethyl-1-methyl-n-propyl group, 1-ethyl-2-methyl-n-propyl group, cyclohexyl group, 1-methyl-cyclopentyl group, 2-methyl-cyclopentyl group, 3-methyl-cyclopentyl group, 1-ethyl-cyclobutyl group, 2-ethyl-cyclobutyl group, 3-ethyl-cyclobutyl group, 1,2-dimethyl-cyclobutyl group, 1,3-dimethyl-cyclobutyl group, 2,2-dimethyl-cyclobutyl group, 2,3-dimethyl-cyclobutyl group, 2,4-dimethyl-cyclobutyl group, 3,3-dimethyl-cyclobutyl group, 1-n-propyl-cyclopropyl group, 2-n-propyl Examples of the cyclopropyl group include 1-i-propyl-cyclopropyl group, 2-i-propyl-cyclopropyl group, 1,2,2-trimethyl-cyclopropyl group, 1,2,3-trimethyl-cyclopropyl group, 2,2,3-trimethyl-cyclopropyl group, 1-ethyl-2-methyl-cyclopropyl group, 2-ethyl-1-methyl-cyclopropyl group, 2-ethyl-2-methyl-cyclopropyl group, 2-ethyl-3-methyl-cyclopropyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, and icodecyl group.

Examples of "alkoxy groups having 1 to 20 carbon atoms" include methoxy groups, ethoxy groups, n-propoxy groups, i-propoxy groups, n-butoxy groups, i-butoxy groups, s-butoxy groups, t-butoxy groups, n-pentyloxy groups, 1-methyl-n-butoxy groups, 2-methyl-n-butoxy groups, 3-methyl-n-butoxy groups, 1,1-dimethyl-n-propoxy groups, 1,2-dimethyl-n-propoxy groups, 2,2-dimethyl-n-propoxy groups, 1-ethyl-n-propoxy groups, n-hexyloxy groups, 1-methyl-n-pentyloxy groups, 2-methyl-n-pentyloxy groups, 3-methyl-n-pentyloxy groups, 4-methyl-n-pentyloxy groups, 1,1-dimethyl-n-butoxy groups, 1,2 -Dimethyl-n-butoxy group, 1,3-dimethyl-n-butoxy group, 2,2-dimethyl-n-butoxy group, 2,3-dimethyl-n-butoxy group, 3,3-dimethyl-n-butoxy group, 1-ethyl-n-butoxy group, 2-ethyl-n-butoxy group, 1,1,2-trimethyl-n-propoxy group, 1,2,2-trimethyl-n-propoxy group, 1-ethyl-1-methyl-n-propoxy group, 1-ethyl-2-methyl-n-propoxy group, cyclopentyloxy group, cyclohexyloxy group, norbornyloxy group, adamantyloxy group, adamantanemethyloxy group, adamantaneethyloxy group, tetracyclodecanyloxy group, tricyclodecanyloxy group, etc.

The "acyloxy group having 1 to 10 carbon atoms" is represented by the following formula (20):

（式（２０）中、Ｚは水素原子、又は上記「炭素原子数１～１０のアルキル基」中の「炭素原子数１～９のアルキル基」を表し、＊は上記「脂肪族環」との結合部分を表す。）で表されるものを言う。

(In formula (20), Z represents a hydrogen atom or an "alkyl group having 1 to 9 carbon atoms" in the above-mentioned "alkyl group having 1 to 10 carbon atoms", and * represents the bonding portion to the above-mentioned "aliphatic ring".)

Examples of "alkenyl groups having 3 to 6 carbon atoms" include 1-propenyl, 2-propenyl, 1-methyl-1-ethenyl, 1-butenyl, 2-butenyl, 3-butenyl, 2-methyl-1-propenyl, 2-methyl-2-propenyl, 1-ethylethenyl, 1-methyl-1-propenyl, 1-methyl-2-propenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 1-n-propylethenyl, 1 -methyl-1-butenyl group, 1-methyl-2-butenyl group, 1-methyl-3-butenyl group, 2-ethyl-2-propenyl group, 2-methyl-1-butenyl group, 2-methyl-2-butenyl group, 2-methyl-3-butenyl group, 3-methyl-1-butenyl group, 3-methyl-2-butenyl group, 3-methyl-3-butenyl group, 1,1-dimethyl-2-propenyl group, 1-i-propylethenyl group, 1,2-dimethyl-1-propenyl group, 1,2-dimethyl-2- propenyl group, 1-cyclopentenyl group, 2-cyclopentenyl group, 3-cyclopentenyl group, 1-hexenyl group, 2-hexenyl group, 3-hexenyl group, 4-hexenyl group, 5-hexenyl group, 1-methyl-1-pentenyl group, 1-methyl-2-pentenyl group, 1-methyl-3-pentenyl group, 1-methyl-4-pentenyl group, 1-n-butylethenyl group, 2-methyl-1-pentenyl group, 2-methyl-2-pentenyl group, 2-methyl-3-pentenyl group, phenyl group, 2-methyl-4-pentenyl group, 2-n-propyl-2-propenyl group, 3-methyl-1-pentenyl group, 3-methyl-2-pentenyl group, 3-methyl-3-pentenyl group, 3-methyl-4-pentenyl group, 3-ethyl-3-butenyl group, 4-methyl-1-pentenyl group, 4-methyl-2-pentenyl group, 4-methyl-3-pentenyl group, 4-methyl-4-pentenyl group, 1,1-dimethyl-2-butenyl group, 1,1-dimethyl-3-butenyl group, butylethenyl group, 1,2-dimethyl-1-butenyl group, 1,2-dimethyl-2-butenyl group, 1,2-dimethyl-3-butenyl group, 1-methyl-2-ethyl-2-propenyl group, 1-s-butylethenyl group, 1,3-dimethyl-1-butenyl group, 1,3-dimethyl-2-butenyl group, 1,3-dimethyl-3-butenyl group, 1-i-butylethenyl group, 2,2-dimethyl-3-butenyl group, 2,3-dimethyl-1-butenyl group, 2,3-dimethyl-2-butenyl group, a-butenyl group, 2,3-dimethyl-3-butenyl group, 2-i-propyl-2-propenyl group, 3,3-dimethyl-1-butenyl group, 1-ethyl-1-butenyl group, 1-ethyl-2-butenyl group, 1-ethyl-3-butenyl group, 1-n-propyl-1-propenyl group, 1-n-propyl-2-propenyl group, 2-ethyl-1-butenyl group, 2-ethyl-2-butenyl group, 2-ethyl-3-butenyl group, 1,1,2-trimethyl-2-propenyl group, 1-t -butylethenyl group, 1-methyl-1-ethyl-2-propenyl group, 1-ethyl-2-methyl-1-propenyl group, 1-ethyl-2-methyl-2-propenyl group, 1-i-propyl-1-propenyl group, 1-i-propyl-2-propenyl group, 1-methyl-2-cyclopentenyl group, 1-methyl-3-cyclopentenyl group, 2-methyl-1-cyclopentenyl group, 2-methyl-2-cyclopentenyl group, 2-methyl-3-cyclopentenyl group, 2- Examples include methyl-4-cyclopentenyl group, 2-methyl-5-cyclopentenyl group, 2-methylene-cyclopentyl group, 3-methyl-1-cyclopentenyl group, 3-methyl-2-cyclopentenyl group, 3-methyl-3-cyclopentenyl group, 3-methyl-4-cyclopentenyl group, 3-methyl-5-cyclopentenyl group, 3-methylene-cyclopentyl group, 1-cyclohexenyl group, 2-cyclohexenyl group, and 3-cyclohexenyl group.

Examples of "alkylthio groups having 1 to 6 carbon atoms" include methylthio groups, ethylthio groups, propylthio groups, butylthio groups, pentylthio groups, and hexylthio groups.

"Halogen atoms" include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

Examples of "arylene groups having 6 to 40 carbon atoms" include phenylene groups, o-methylphenylene groups, m-methylphenylene groups, p-methylphenylene groups, o-chlorophenylene groups, m-chlorophenylene groups, p-chlorophenylene groups, o-fluorophenylene groups, p-fluorophenylene groups, o-methoxyphenylene groups, p-methoxyphenylene groups, p-nitrophenylene groups, p-cyanophenylene groups, α-naphthylene groups, β-naphthylene groups, o-biphenylylene groups, m-biphenylylene groups, p-biphenylylene groups, 1-anthrylene groups, 2-anthrylene groups, 9-anthrylene groups, 1-phenanthrylene groups, 2-phenanthrylene groups, 3-phenanthrylene groups, 4-phenanthrylene groups, and 9-phenanthrylene groups.

<Resist Underlayer Film Forming Composition>
The resist underlayer film forming composition of the present application contains, at an end of a polymer contained in the resist underlayer film forming composition, an aliphatic ring in which a carbon-carbon bond may be interrupted by a heteroatom and an aliphatic ring which may be further substituted with a substituent, and further contains an organic solvent.

The carbon-carbon bond may be interrupted by a heteroatom, which means that the carbon-carbon bond of the aliphatic ring of this application includes an -O- or -S- bond between the carbon-carbon bonds.

An aliphatic ring that may be substituted with a substituent refers to an aliphatic ring in which all or some of the hydrogen atoms are substituted with, for example, a hydroxy group, a linear or branched alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an acyloxy group having 1 to 10 carbon atoms, or a carboxy group.

The aliphatic ring is preferably a monocyclic or polycyclic aliphatic ring having 3 to 10 carbon atoms.

Examples of "monocyclic or polycyclic aliphatic ring having 3 to 10 carbon atoms" include cyclopropane, cyclobutane, cyclopentane, cyclohexane, cyclohexene, cycloheptane, cyclooctane, cyclononane, cyclodecane, spirobicyclopentane, bicyclo[2.1.0]pentane, bicyclo[3.2.1]octane, tricyclo[3.2.1.0 ^2,7 ]octane, spiro[3,4]octane, norbornane, norbornene, tricyclo[3.3.1.1 ^3,7 ]decane (adamantane), and the like.

The polycyclic aliphatic ring is preferably a bicyclo ring or a tricyclo ring.
Among these, examples of the bicyclo ring include norbornane, norbornene, spiro-bicyclopentane, bicyclo[2.1.0]pentane, bicyclo[3.2.1]octane, and spiro[3,4]octane.
Among these, examples of the tricyclo ring include tricyclo[3.2.1.0 ^2,7 ]octane and tricyclo[3.3.1.1 ^3,7 ]decane (adamantane).

The aliphatic ring preferably has at least one unsaturated bond (e.g., a double bond or a triple bond). The aliphatic ring preferably has one to three unsaturated bonds. The aliphatic ring preferably has one or two unsaturated bonds. The unsaturated bond is preferably a double bond.

Specific examples of "aliphatic rings in which the carbon-carbon bond may be interrupted by a heteroatom and which may be substituted with a substituent" are derived by reacting the compounds described below with the terminals of the polymer by a method known per se.

It is preferable that the polymer has at least one structural unit represented by the following formula (3) in the main chain.

(In formula (3), A ₁ , A ₂ , A ₃ , A ₄ , A ₅ and A ₆ each independently represent a hydrogen atom, a methyl group or an ethyl group, Q ₁ represents a divalent organic group, and m ₁ and m ₂ each independently represent 0 or 1.)
In the formula (3), Q ₁ preferably represents a divalent organic group represented by the following formula (5).

(In the formula, Y represents a divalent group represented by the following formula (6) or formula (7).)

(In the formula, R ₆ and R ₇ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 3 to 6 carbon atoms, a benzyl group, or a phenyl group, and the phenyl group may be substituted with at least one selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, and an alkylthio group having 1 to 6 carbon atoms, or R ₆ and R ₇ may be bonded to each other to form a ring having 3 to 6 carbon atoms together with the carbon atoms bonded to R ₆ and R _7. )

Examples of "rings having 3 to 6 carbon atoms" include cyclopropane, cyclobutane, cyclopentane, cyclopentadiene, and cyclohexane.

It is preferable that the polymer further contains a disulfide bond in the main chain.

The polymer preferably contains an arylene group having 6 to 40 carbon atoms, which may be substituted with a substituent. The meaning of the substituent is the same as described above.

The weight average molecular weight of the polymer is, for example, 2,000 to 50,000.

Examples of the monomer forming the structural unit represented by the formula (3) in which _m1 and _{m2 each} represent 1 include compounds having two epoxy groups represented by the following formulae (10-a) to (10-k):

Specific examples include, but are not limited to, 1,4-terephthalic acid diglycidyl, 2,6-naphthalenedicarboxylate diglycidyl, 1,6-dihydroxynaphthalenediglycidyl, 1,2-cyclohexanedicarboxylate diglycidyl, 2,2-bis(4-hydroxyphenyl)propane diglycidyl, 2,2-bis(4-hydroxycyclohexane)propane diglycidyl, 1,4-butanediol diglycidyl, monoallyl isocyanurate diglycidyl, monomethyl isocyanurate diglycidyl, 5,5-diethylbarbiturate diglycidyl, and 5,5-dimethylhydantoin diglycidyl.

Examples of the monomer forming the structural unit represented by the formula (3) in which _m1 and _m2 are 0 include compounds having two carboxyl groups, hydroxyphenyl groups, or imide groups, and acid dianhydrides, which are represented by the following formulas (11-a) to (11-s):

That is, isophthalic acid, 5-hydroxyisophthalic acid, 2,4-dihydroxybenzoic acid, 2,2-bis(4-hydroxyphenyl)sulfone, succinic acid, fumaric acid, tartaric acid, 3,3'-dithiodipropionic acid, 1,4-cyclohexanedicarboxylic acid, cyclobutanoic dianhydride, cyclopentanoic dianhydride, monoallyl isocyanuric acid, 5,5-diethylbarbituric acid, diglycolic acid, acetonedicarboxylic acid, 2,2'-thiodiglycolic acid, 4-hydroxybenzoic acid-4-hydroxyphenyl, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 1,3-bis(carboxymethyl)-5-methylisocyanurate, 1,3-bis(carboxymethyl)-5-allylisocyanurate, but are not limited to these examples.

The copolymerization ratio (feed weight ratio) of the monomer (bifunctional) forming the structural unit represented by the formula (3) in which _m1 and _m2 are 1 and the monomer (bifunctional) forming the structural unit represented by the formula (3) in which _m1 and _m2 are 0 is, for example, 1:2 to 2:1.
Furthermore, the weight ratio of the monomer for inducing an aliphatic ring bonded to the polymer terminal of the present invention (the site that mainly reacts with the polymer is monofunctional) to the total of the above monomers is, for example, 20:1 to 5:1.
"Functionality" is a concept that focuses on the chemical attributes and chemical reactivity of a substance. When referring to a functional group, each is assumed to have its own inherent physical properties and chemical reactivity, but in this application, it refers to a reactive substituent that can bond with other compounds.
The number of repetitions of the structural unit represented by the formula (3) is, for example, in the range of 5 to 10,000.

Examples of the organic solvent contained in the resist underlayer film forming composition of the present invention include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, propylene glycol propyl ether acetate, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cyclopentane, Examples of the solvent include cyclohexanone, cycloheptanone, 4-methyl-2-pentanol, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, ethyl ethoxyacetate, 2-hydroxyethyl acetate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethyl acetate, butyl acetate, ethyl lactate, butyl lactate, 2-heptanone, methoxycyclopentane, anisole, γ-butyrolactone, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide. These solvents can be used alone or in combination of two or more.
Among these solvents, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, butyl lactate, cyclohexanone, etc. are preferred, with propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate being particularly preferred.
The ratio of the organic solvent to the resist underlayer film forming composition of the present invention is, for example, 50% by mass or more and 99.9% by mass or less.
The amount of the polymer contained in the resist underlayer film forming composition of the present invention is, for example, 0.1% by mass to 50% by mass with respect to the resist underlayer film forming composition.

The resist underlayer film-forming composition of the present invention may contain, in addition to the polymer and organic solvent, a crosslinking agent and a crosslinking catalyst (curing catalyst) which is a compound that promotes a crosslinking reaction. If the components excluding the organic solvent from the resist underlayer film-forming composition of the present invention are defined as the solid content, the solid content includes the polymer and additives such as a crosslinking agent and a crosslinking catalyst which are added as necessary. The proportion of the additives is, for example, 0.1% by mass to 50% by mass, preferably 1% by mass to 30% by mass, based on the solid content of the resist underlayer film-forming composition of the present invention.

Examples of crosslinking agents that may be included as optional components in the resist underlayer film forming composition of the present invention include hexamethoxymethylmelamine, tetramethoxymethylbenzoguanamine, 1,3,4,6-tetrakis(methoxymethyl)glycoluril (tetramethoxymethylglycoluril) (POWDERLINK [registered trademark] 1174), 1,3,4,6-tetrakis(butoxymethyl)glycoluril, 1,3,4,6-tetrakis(hydroxymethyl)glycoluril, 1,3-bis(hydroxymethyl)urea, 1,1,3,3-tetrakis(butoxymethyl)urea, 1,1,3,3-tetrakis(methoxymethyl)urea, and 3,3',5,5'-tetrakis(methoxymethyl)4,4'-biphenol. When the above crosslinking agents are used, the content of the crosslinking agent is, for example, 1% by mass to 50% by mass, and preferably 5% by mass to 30% by mass, relative to the polymer.

Examples of the curing catalyst (crosslinking catalyst) contained as an optional component in the resist underlayer film forming composition of the present invention include sulfonic acid compounds and carboxylic acid compounds such as p-toluenesulfonic acid, trifluoromethanesulfonic acid, pyridinium-p-toluenesulfonate (pyridinium-p-toluenesulfonic acid), pyridinium-p-hydroxybenzenesulfonic acid, pyridinium-trifluoromethanesulfonic acid, cyclohexyl p-toluenesulfonate, morpholine, p-toluenesulfonate, salicylic acid, camphorsulfonic acid, 5-sulfosalicylic acid, 4-chlorobenzenesulfonic acid, 4-hydroxybenzenesulfonic acid, benzenedisulfonic acid, 1-naphthalenesulfonic acid, citric acid, benzoic acid, and hydroxybenzoic acid. When the above-mentioned crosslinking catalyst is used, the content of the crosslinking catalyst is, for example, 0.1% by mass to 50% by mass, and preferably 1% by mass to 30% by mass, relative to the crosslinking agent.

The resist underlayer film forming composition of the present invention can further contain a surfactant in order to prevent pinholes, striations, etc., and to further improve the coating property against surface unevenness. Examples of the surfactant include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, and polyoxyethylene oleyl ether, polyoxyethylene alkyl allyl ethers such as polyoxyethylene octylphenol ether and polyoxyethylene nonylphenol ether, polyoxyethylene-polyoxypropylene block copolymers, sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, and sorbitan tristearate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, and the like. nonionic surfactants such as polyoxyethylene sorbitan fatty acid esters, such as polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, and polyoxyethylene sorbitan tristearate; fluorosurfactants such as EFTOP EF301, EF303, and EF352 (trade names, manufactured by Tochem Products Co., Ltd.), Megafac F171, F173, and R-30 (trade names, manufactured by Dainippon Ink Co., Ltd.), Fluorad FC430 and FC431 (trade names, manufactured by Sumitomo 3M Limited), Asahi Guard AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105, and SC106 (trade names, manufactured by Asahi Glass Co., Ltd.); and organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.). The amount of these surfactants is usually 2.0% by mass or less, preferably 1.0% by mass or less, based on the total solid content of the resist underlayer film forming composition of the present invention. These surfactants may be added alone or in combination of two or more.

<Resist Underlayer Film>
The resist underlayer film according to the present invention can be produced by applying the above-mentioned resist underlayer film-forming composition onto a semiconductor substrate and baking it.
Examples of semiconductor substrates to which the resist underlayer film forming composition of the present invention can be applied include silicon wafers, germanium wafers, and wafers of compound semiconductors such as gallium arsenide, indium phosphide, gallium nitride, indium nitride, and aluminum nitride.
When a semiconductor substrate having an inorganic film formed on its surface is used, the inorganic film is formed by, for example, ALD (atomic layer deposition), CVD (chemical vapor deposition), reactive sputtering, ion plating, vacuum deposition, or spin coating (spin-on glass: SOG). Examples of the inorganic film include a polysilicon film, a silicon oxide film, a silicon nitride film, a BPSG (Boro-Phospho Silicate Glass) film, a titanium nitride film, a titanium nitride oxide film, a tungsten film, a gallium nitride film, and a gallium arsenide film.
The resist underlayer film forming composition of the present invention is applied onto such a semiconductor substrate by a suitable application method such as a spinner or coater. Then, the composition is baked using a heating means such as a hot plate to form a resist underlayer film. The baking conditions are appropriately selected from a baking temperature of 100° C. to 400° C. and a baking time of 0.3 minutes to 60 minutes. Preferably, the baking temperature is 120° C. to 350° C. and the baking time is 0.5 minutes to 30 minutes, and more preferably, the baking temperature is 150° C. to 300° C. and the baking time is 0.8 minutes to 10 minutes.
The thickness of the resist underlayer film formed may be, for example, 0.001 μm (1 nm) to 10 μm, 0.002 μm (2 nm) to 1 μm, 0.005 μm (5 nm) to 0.5 μm (500 nm), 0.001 μm (1 nm) to 0.05 μm (50 nm), 0.002 μm (2 nm) to 0.05 μm (50 nm), 0.003 μm (1 nm) to 0.05 μm (50 nm), ) to 0.05 μm (50 nm), 0.004 μm (4 nm) to 0.05 μm (50 nm), 0.005 μm (5 nm) to 0.05 μm (50 nm), 0.003 μm (3 nm) to 0.03 μm (30 nm), 0.003 μm (3 nm) to 0.02 μm (20 nm), 0.005 μm (5 nm) to 0.02 μm (20 nm). If the baking temperature is lower than the above range, crosslinking may be insufficient. On the other hand, if the baking temperature is higher than the above range, the resist underlayer film may be decomposed by heat.

<Method for manufacturing a patterned substrate, and method for manufacturing a semiconductor device>
The manufacturing method of the patterned substrate includes the following steps. Usually, a photoresist layer is formed on a resist underlayer film. The photoresist formed by coating and baking on the resist underlayer film by a method known per se is not particularly limited as long as it is sensitive to the light used for exposure. Either a negative photoresist or a positive photoresist can be used. Examples of the photoresist include a positive photoresist made of a novolac resin and a 1,2-naphthoquinone diazide sulfonic acid ester, a chemically amplified photoresist made of a binder having a group that decomposes with an acid to increase the alkaline dissolution rate and a photoacid generator, a chemically amplified photoresist made of a low molecular compound that decomposes with an acid to increase the alkaline dissolution rate of the photoresist, an alkali-soluble binder, and a photoacid generator, a chemically amplified photoresist made of a binder having a group that decomposes with an acid to increase the alkaline dissolution rate, a low molecular compound that decomposes with an acid to increase the alkaline dissolution rate of the photoresist, and a photoacid generator, and a resist containing a metal element. Examples of such photoresists include V146G (trade name) manufactured by JSR Corporation, APEX-E (trade name) manufactured by Shipley Co., Ltd., PAR710 (trade name) manufactured by Sumitomo Chemical Co., Ltd., and AR2772 and SEPR430 (trade names) manufactured by Shin-Etsu Chemical Co., Ltd. Further examples of such photoresists include fluorine atom-containing polymer photoresists as described in Proc. SPIE, Vol. 3999, 330-334 (2000), Proc. SPIE, Vol. 3999, 357-364 (2000), and Proc. SPIE, Vol. 3999, 365-374 (2000).

Exposure is performed through a mask (reticle) for forming a predetermined pattern, and for example, i-line, KrF excimer laser, ArF excimer laser, EUV (extreme ultraviolet) or EB (electron beam) is used, but the resist underlayer film forming composition of the present application is preferably applied for EUV (extreme ultraviolet) exposure. An alkaline developer is used for development, and the development temperature is appropriately selected from 5°C to 50°C and the development time is appropriately selected from 10 seconds to 300 seconds. As the alkaline developer, for example, aqueous solutions of alkalis such as inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, and ammonia water, primary amines such as ethylamine and n-propylamine, secondary amines such as diethylamine and di-n-butylamine, tertiary amines such as triethylamine and methyldiethylamine, alcohol amines such as dimethylethanolamine and triethanolamine, quaternary ammonium salts such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and choline, cyclic amines such as pyrrole and piperidine, etc. can be used. Furthermore, an appropriate amount of alcohol such as isopropyl alcohol or a nonionic surfactant can be added to the aqueous solution of the above alkalis. Among these, preferred developers are quaternary ammonium salts, more preferably tetramethylammonium hydroxide and choline. Furthermore, surfactants can be added to these developers. Instead of an alkaline developer, a method can be used in which development is performed with an organic solvent such as butyl acetate, and the parts of the photoresist where the alkaline dissolution rate is not improved are developed. Through the above steps, a substrate on which the resist is patterned can be manufactured.

Then, the resist underlayer film is dry etched using the formed resist pattern as a mask. In this case, if the inorganic film is formed on the surface of the semiconductor substrate used, the surface of the inorganic film is exposed, and if the inorganic film is not formed on the surface of the semiconductor substrate used, the surface of the semiconductor substrate is exposed. The substrate is then processed by a method known per se (dry etching method, etc.), and a semiconductor device can be manufactured.

The present invention will now be described in detail with reference to examples, but the present invention is not limited to these.
The weight average molecular weights of the polymers shown in Synthesis Examples 1 to 8 and Comparative Synthesis Examples 1 and 2 below in this specification are the results of measurement by gel permeation chromatography (hereinafter abbreviated as GPC). For the measurement, a GPC device manufactured by Tosoh Corporation was used, and the measurement conditions, etc. are as follows.
GPC column: Shodex KF803L, Shodex KF802, Shodex KF801 (registered trademark) (Showa Denko K.K.)
Column temperature: 40°C
Solvent: Tetrahydrofuran (THF)
Flow rate: 1.0 ml/min. Standard sample: polystyrene (manufactured by Tosoh Corporation)

<Synthesis Example 1>
As polymer 1, 7.88 g of N,N-diglycidyl-5,5-dimethylhydantoin (manufactured by Shikoku Chemical Industry Co., Ltd.), 5.03 g of monoallyl isocyanuric acid (manufactured by Shikoku Chemical Industry Co., Ltd.), 1.45 g of 5-norbornene-2-carboxylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), and 0.65 g of ethyltriphenylphosphonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) were added and dissolved in 66.60 g of propylene glycol monomethyl ether. After replacing the reaction vessel with nitrogen, the mixture was reacted at 110°C for 24 hours to obtain a polymer solution. When GPC analysis was performed, the obtained polymer had a weight average molecular weight of 3000 and a dispersity of 2.8 in terms of standard polystyrene. The structure present in polymer 1 is shown in the following formula.

<Synthesis Example 2>
As polymer 2, 7.88 g of N,N-diglycidyl-5,5-dimethylhydantoin (manufactured by Shikoku Chemical Industry Co., Ltd.), 5.07 g of monoallyl isocyanuric acid (manufactured by Shikoku Chemical Industry Co., Ltd.), 1.34 g of 3-cyclohexene-1-carboxylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), and 0.66 g of ethyltriphenylphosphonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) were added and dissolved in 66.60 g of propylene glycol monomethyl ether. After replacing the reaction vessel with nitrogen, the mixture was reacted at 110°C for 24 hours to obtain a polymer solution. When GPC analysis was performed, the obtained polymer had a weight average molecular weight of 2500 and a dispersity of 2.2 in terms of standard polystyrene. The structure present in polymer 2 is shown in the following formula.

<Synthesis Example 3>
As polymer 3, 7.95 g of N,N-diglycidyl-5,5-dimethylhydantoin (manufactured by Shikoku Chemical Industry Co., Ltd.), 5.07 g of monoallyl isocyanuric acid (manufactured by Shikoku Chemical Industry Co., Ltd.), 1.74 g of 5-norbornene-2,3-dicarboxylic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd.), and 0.66 g of ethyltriphenylphosphonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) were added and dissolved in 66.60 g of propylene glycol monomethyl ether. After replacing the reaction vessel with nitrogen, the mixture was reacted at 110°C for 24 hours to obtain a polymer solution. When GPC analysis was performed, the obtained polymer had a weight average molecular weight of 2500 and a dispersity of 2.2 in terms of standard polystyrene. The structure present in polymer 3 is shown in the following formula.

<Synthesis Example 4>
As polymer 4, 7.88 g of N,N-diglycidyl-5,5-dimethylhydantoin (manufactured by Shikoku Chemical Industry Co., Ltd.), 5.07 g of monoallyl isocyanuric acid (manufactured by Shikoku Chemical Industry Co., Ltd.), 1.73 g of cyclohexane-1-carboxylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), and 0.63 g of ethyltriphenylphosphonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) were added and dissolved in 66.60 g of propylene glycol monomethyl ether. After replacing the reaction vessel with nitrogen, the mixture was reacted at 110°C for 24 hours to obtain a polymer solution. When GPC analysis was performed, the obtained polymer had a weight average molecular weight of 2500 and a dispersity of 2.2 in terms of standard polystyrene. The structure present in polymer 4 is shown in the following formula.

<Synthesis Example 5>
As polymer 5, 7.73 g of N,N-diglycidyl-5,5-dimethylhydantoin (manufactured by Shikoku Chemical Industry Co., Ltd.), 4.94 g of monoallyl isocyanuric acid (manufactured by Shikoku Chemical Industry Co., Ltd.), 1.71 g of 7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd.) and 0.64 g of ethyltriphenylphosphonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) were added and dissolved in 66.60 g of propylene glycol monomethyl ether. After replacing the reaction vessel with nitrogen, the mixture was reacted at 110°C for 24 hours to obtain a polymer solution. When GPC analysis was performed, the obtained polymer had a weight average molecular weight of 2500 and a dispersity of 2.0 in terms of standard polystyrene. The structure present in polymer 5 is shown in the following formula.

<Synthesis Example 6>
As polymer 6, 7.20 g of N,N-diglycidyl-5,5-dimethylhydantoin (manufactured by Shikoku Chemical Industry Co., Ltd.), 4.95 g of 5-hydroxyisophthalic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 1.33 g of 5-norbornene-2-carboxylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) and 0.54 g of ethyltriphenylphosphonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) were added and dissolved in 39.19 g of propylene glycol monomethyl ether. After replacing the reaction vessel with nitrogen, the mixture was reacted at 110°C for 24 hours to obtain a polymer solution. When GPC analysis was performed, the obtained polymer had a weight average molecular weight of 2500 and a dispersity of 2.2 in terms of standard polystyrene. The structure present in polymer 6 is shown in the following formula.

<Synthesis Example 7>
As polymer 7, 25.00 g of monoallyl diglycidyl isocyanuric acid (manufactured by Shikoku Chemical Industry Co., Ltd.), 14.72 g of diethyl barbituric acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 2.91 g of 5-norbornene-2,3-dicarboxylic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd.) and 1.64 g of ethyl triphenylphosphonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) were added and dissolved in 89.73 g of propylene glycol monomethyl ether. After replacing the reaction vessel with nitrogen, the mixture was reacted at 110°C for 24 hours to obtain a polymer solution. When GPC analysis was performed, the obtained polymer had a weight average molecular weight of 3000 and a dispersity of 2.3 in terms of standard polystyrene. The structure present in polymer 7 is shown in the following formula.

<Synthesis Example 8>
As polymer 8, 25.00 g of monoallyl diglycidyl isocyanuric acid (manufactured by Shikoku Chemical Industry Co., Ltd.), 15.86 g of dithiodipropanoic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 4.80 g of adamantanecarboxylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) and 1.13 g of tetrabutylphosphonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) were added and dissolved in 57.12 g of propylene glycol monomethyl ether. After replacing the reaction vessel with nitrogen, the reaction was carried out at 110 ° C. for 24 hours to obtain a polymer solution. When GPC analysis was performed, the obtained polymer had a weight average molecular weight of 5000 and a dispersity of 2.3 in terms of standard polystyrene. The structure present in polymer 8 is shown in the following formula.

<Synthesis Example 9>
As polymer 9, 25.00 g of monoallyl diglycidyl isocyanuric acid (manufactured by Shikoku Chemical Industry Co., Ltd.), 15.86 g of dithiodipropanoic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 3.68 g of 5-norbornene-2-carboxylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) and 1.13 g of tetrabutylphosphonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) were added and dissolved in 57.12 g of propylene glycol monomethyl ether. After replacing the reaction vessel with nitrogen, the mixture was reacted at 110° C. for 24 hours to obtain a polymer solution. When GPC analysis was performed, the obtained polymer had a weight average molecular weight of 5000 and a dispersity of 2.5 in terms of standard polystyrene. The structure present in polymer 9 is shown in the following formula.

Comparative Synthesis Example 1
As polymer 10, 21.90 g of monoallyl diglycidyl isocyanuric acid (manufactured by Shikoku Chemical Industry Co., Ltd.), 12.17 g of diethyl barbituric acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 4.67 g of lauric acid (manufactured by Tokyo Chemical Industry Co., Ltd.) and 0.56 g of ethyl triphenyl phosphonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) were added and dissolved in 89.73 g of propylene glycol monomethyl ether. After replacing the reaction vessel with nitrogen, the reaction was carried out at 110 ° C. for 24 hours to obtain a polymer solution. When GPC analysis was performed, the obtained polymer had a weight average molecular weight of 3000 and a dispersity of 2.2 in terms of standard polystyrene. The structure present in polymer 10 is shown in the following formula.

Comparative Synthesis Example 2
As polymer 11, 25.00 g of monoallyl diglycidyl isocyanuric acid (manufactured by Shikoku Chemical Industry Co., Ltd.), 15.86 g of dithiodipropanoic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), and 1.13 g of tetrabutylphosphonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) were added and dissolved in 57.12 g of propylene glycol monomethyl ether. After replacing the reaction vessel with nitrogen, the reaction was carried out at 110 ° C. for 24 hours to obtain a polymer solution. When GPC analysis was performed, the obtained polymer had a weight average molecular weight of 5000 and a dispersity of 4.3 in terms of standard polystyrene. The structure present in polymer 11 is shown in the following formula.

(Preparation of resist underlayer film)
Example 1
In the above Synthesis Examples 1 to 9 and Comparative Synthesis Examples 1 and 2, the polymer, crosslinking agent, curing catalyst, and solvent were mixed in the ratios shown in Table 1, and the mixture was filtered through a 0.1 μm fluororesin filter to prepare solutions of compositions for forming resist underlayer films.
In Table 1, tetramethoxymethylglycoluril (manufactured by Nippon Cytec Industries Co., Ltd.) is abbreviated as PL-LI, pyridinium-p-toluenesulfonic acid as PyPTS, pyridinium-p-hydroxybenzenesulfonic acid as PyPSA, propylene glycol monomethyl ether acetate as PGMEA, and propylene glycol monomethyl ether as PGME. The amount of each additive is shown in parts by mass.

(Photoresist solvent elution test)
The resist underlayer film forming compositions of Examples 1 to 11, Comparative Example 1, and Comparative Example 2 were applied onto a silicon wafer using a spinner. The silicon wafer was baked on a hot plate at 205° C. for 60 seconds to obtain a film with a thickness of 5 nm. These resist underlayer films were immersed in a mixed solution of propylene glycol monomethyl ether/propylene glycol monomethyl ether=70/30, which is a solvent used in photoresists, and the results are shown in Table 3, with a film thickness change of 1 Å or less being rated as good and a film thickness change of 1 Å or more being rated as bad. Only Comparative Example 1 was rated as bad.

(Measurement of Water Contact Angle)
The resist underlayer film forming compositions of Examples 1 to 11 and Comparative Examples 1 and 2 were applied onto a silicon wafer using a spinner. The silicon wafer was baked on a hot plate at 205° C. for 60 seconds to obtain a film having a thickness of 5 nm. The water contact angles of these resist underlayer films were measured by the sessile drop method using a fully automatic contact angle meter DM-701 (manufactured by Kyowa Interface Science Co., Ltd.).

(Resist patterning evaluation)
[Formation of Resist Pattern by KrF Exposure]
DUV-30J (manufactured by Nissan Chemical Industries, Ltd.) was applied as an anti-reflective film onto a silicon wafer using a spinner. The silicon wafer was baked on a hot plate at 205° C. for 60 seconds to obtain a film with a thickness of 18 nm. The resist underlayer film forming compositions of Examples 1 to 6, Example 8, and Comparative Examples 1 and 2 were applied onto the film onto the silicon wafer using a spinner. The silicon wafer was baked on a hot plate at 205° C. for 60 seconds to obtain a resist underlayer film with a thickness of 5 nm. SEPR-430 (manufactured by Shin-Etsu Chemical Co., Ltd.) was spin-coated onto the resist underlayer film as a positive resist solution for KrF excimer laser, and heated at 100° C. for 60 seconds to form a KrF resist film. The resist film was exposed under predetermined conditions using a KrF excimer laser exposure device (manufactured by Nikon Corporation, NSR S205C). After exposure, post-exposure baking was performed at 110° C. for 60 seconds, and then paddle development was performed for 60 seconds using a 2.38% aqueous solution of tetramethylammonium hydroxide (manufactured by Tokyo Ohka Kogyo Co., Ltd., product name NMD-3) as a photoresist developer. The obtained photoresist patterns were evaluated as good when no significant pattern peeling occurred.

[EUV Exposure Test]
The resist underlayer film forming compositions of Example 9, Example 10 and Comparative Example 2 of the present invention were spin-coated on a silicon wafer, and heated at 215° C. for 1 minute to form a resist underlayer film (film thickness 5 nm). A resist solution for EUV (methacrylate resin-based resist) was spin-coated on the resist underlayer film, heated, and exposed under the condition of NA=0.33 dipole using an EUV exposure device (manufactured by ASML, NXE3300). After exposure, post-exposure baking (PEB, 100° C. for 60 seconds) was performed, and the film was cooled to room temperature on a cooling plate, and alkali development and rinsing treatment were performed to form a resist pattern on the silicon wafer. The evaluation was performed based on whether or not a 16 nm line and space (L/S) was formed. In all cases of Example 9, Example 10 and Comparative Example 2, 16 nm L/S pattern formation was confirmed. The exposure dose at which 16 nm lines/32 nm pitch (line and space (L/S=1/1) were formed was defined as the optimum exposure dose, and the exposure dose (EOP) at that time is shown. Furthermore, the line width roughness (LWR) at that time is shown in Table 5. In Examples 9 and 10, an improvement in LWR was observed compared to Comparative Example 2.

[EUV Exposure Test]
The resist underlayer film forming composition of Example 1 of the present invention was spin-coated on a silicon wafer and heated at 215° C. for 1 minute to form a resist underlayer film (film thickness 5 nm). Further, an EUV resist solution (methacrylate resin-based resist) was spin-coated thereon and heated at 130° C. for 1 minute to form an EUV resist film, and exposed under the conditions of NA=0.33 and dipole using an ASML EUV exposure device (NXE3300B). After exposure, post-exposure baking (PEB, 110° C. for 1 minute) was performed, and the film was cooled to room temperature on a cooling plate, developed for 60 seconds using an organic solvent developer (butyl acetate), and rinsed to form a resist pattern.
In the same manner, resist patterns were formed using each of the compositions obtained in Examples 3, 6 to 8 and Comparative Example 2.
The evaluation was performed by checking whether or not a 44 nm pitch, 22 nm line and space could be formed by observing the pattern shape through cross-section observation of the pattern.
In observing the pattern shape, a state in which the shape was between footing and undercut and there was no significant residue in the space was evaluated as "good", an unfavorable state in which the resist pattern peeled off and collapsed was evaluated as "collapsed", and an unfavorable state in which the upper or lower parts of the resist pattern were in contact with each other was evaluated as "bridge". The results are shown in Table 6.

The resist underlayer film forming composition according to the present invention can provide a composition for forming a resist underlayer film capable of forming a desired resist pattern, a method for producing a substrate having a resist pattern using the resist underlayer film forming composition, and a method for producing a semiconductor device.

Claims (8)

A resist underlayer film-forming composition comprising a polymer including an aliphatic ring, at an end of the polymer, in which a carbon-carbon bond may be interrupted by a heteroatom and which may be substituted by a substituent, and an organic solvent , wherein a monomer for deriving the aliphatic ring bonded to the polymer end is selected from the group consisting of compounds of the following formulas :

The resist underlayer film forming composition, wherein the polymer has at least one structural unit represented by the following formula (3) in its main chain:

(In formula (3), A ₁ , A ₂ , A ₃ , A ₄ , A ₅ and A ₆ each independently represent a hydrogen atom, a methyl group or an ethyl group, Q ₁ represents a divalent organic group, and m ₁ and m ₂ each independently represent 0 or 1.) In the formula (3), Q ₁ The resist underlayer film forming composition according to claim 1 , wherein:

(In the formula, Y represents a divalent group represented by the following formula (6) or formula (7).)

(Wherein, R ₆ and R ₇ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 3 to 6 carbon atoms, a benzyl group, or a phenyl group, the phenyl group being optionally substituted with at least one selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, and an alkylthio group having 1 to 6 carbon atoms, or R ₆ and R ₇ are bonded to each other to form the R ₆ and R ₇ may form a ring having 3 to 6 carbon atoms together with the carbon atom bonded to The resist underlayer film forming composition according to claim 1 , wherein the polymer further comprises a disulfide bond in the main chain. The resist underlayer film forming composition according to claim 1 or 2, further comprising a curing catalyst. The resist underlayer film forming composition according to claim 1 or 2, further comprising a crosslinking agent. A resist underlayer film, which is a fired product of a coating film comprising the resist underlayer film forming composition according to any one of claims 1 to 5. A method for producing a patterned substrate, comprising the steps of: applying the resist underlayer film forming composition according to any one of claims 1 to 5 onto a semiconductor substrate and baking the composition to form a resist underlayer film; applying a resist onto the resist underlayer film and baking the composition to form a resist film; exposing the resist underlayer film and the semiconductor substrate covered with the resist to light; and developing and patterning the resist film after exposure. A step of forming a resist underlayer film on a semiconductor substrate, the resist underlayer film being composed of the resist underlayer film forming composition according to any one of claims 1 to 5;
forming a resist film on the resist underlayer film;
forming a resist pattern by irradiating the resist film with light or an electron beam and then developing it;
forming a patterned resist underlayer film by etching the resist underlayer film through the formed resist pattern;
processing a semiconductor substrate using the patterned resist underlayer film;
A method for manufacturing a semiconductor device, comprising: